/in/foo.cc: In function 'int main()':
/in/foo.cc:18:6: warning: variable 'b' set but not used [-Wunused-but-set-variable]
  int b, e;//当前保留
      ^
/in/foo.cc:19:6: warning: unused variable 'b1' [-Wunused-variable]
  int b1, e1;
      ^~
/in/foo.cc:19:10: warning: unused variable 'e1' [-Wunused-variable]
  int b1, e1;
          ^~